The invention relates generally to systems for measuring range and synchronizing clocks on moving and non-moving platforms, and more particularly, to a balanced system for ranging and synchronization between a pair of satellites.
There is an increasing class of satellite pair applications that requires the clocks on the satellite pair to be synchronized. Examples include utilizing the satellite pair for triangulation navigation or for synchronous characterization of independent regions of space.
Existing systems for intersatellite clock synchronization employ measurements to determine the time difference between the clock on each satellite and a ground-based standard. After determination of these time differences, a correction factor is computed and applied to each satellite clock. An example of an existing system is the NAVSTAR Global Positioning System.
These existing systems have many inherent problems including deleterious signal effects indroduced by the earth's atmosphere, limited times for viewing satellites from ground sites, and spectrum restrictions. As a result of these problems, existing systems are accurate to only several tens of nanoseconds. Additionally, it should be noted that these systems do not actually synchronize the clocks, but only compute correction factors that compensate for asynchronisms.
The range between satellites is also measured by systems utilizing ground sites and the resulting range measurements are accurate to only about ten meters.